Scuticociliatosis caused by Uronema sp. in ten different ornamental aquarium reef fish in Brazil.

Scuticociliatosis, caused by an opportunistic ciliate protozoan, is responsible for significant economic losses in marine ornamental fish. This study reports the occurrence of Uronema spp., parasitizing ten species of marine reef fish at an ornamental fish wholesaler: Blue green damselfish (Chromis viridis), Vanderbilt's Chromis (Chromis vanderbilti), Pennant coralfish (Heniochus acuminatus), Threespot angelfish (Apolemichthys trimaculatus), Goldspotted angelfish (Apolemichthys xanthopunctatus), Sea goldie (Pseudanthias squamipinnis), Orchid dottyback (Pseudochromis fridmani), Threadfin butterflyfish (Chaetodon auriga), Vagabond butterflyfish (Chaetodon vagabundus), and Bluecheek butterflyfish (Chaetodon semilarvatus). Diseased fish showed disorders such as hemorrhages and ulcerative lesions on the body surface. Histopathological analysis of the muscle, liver, gut, kidney, spleen, gills, and stomach revealed hemorrhages and degeneration of muscle fiber, vacuolar degeneration of hepatocyte, inflammatory process and granuloma in the liver, atrophy of intestinal villi, inflammatory process and granuloma in the kidney, melanomacrophage centers, as well as inflammatory process in the spleen, epithelial cells hyperplasia and granuloma formation in the gills, and vacuolar degeneration and eosinophils in the stomach. Due to the severity of the disease, it is necessary to implement biosecurity measures with rapid and accurate diagnosis to minimize the risk of economic losses caused by Uronema spp.

Histopathological changes and piscidin 5-like location in infected Larimichthys crocea with parasite Cryptocaryon irritans.

Cryptocaryon irritans infection could cause huge economic losses to the marine fish industry. Larimichthys crocea, a special economic species in China, suffered from the threat of serious infection, and L. crocea could enhance the level of piscidin 5-like to defense against the infection. This study set out to observe the main histopathological changes of some key tissues caused by infection, and determineed how an ectoparasite affected the expression of piscidin-5 like in its hosts. Pathological changes and immune response were assessed using histological and in situ hybridization (ISH) technologies. The infection induced inflammation occurring, especially in the gill where epithelium cells swell, hyperplasia, necrosis shedding adjacent to the parasites attachment sites. Infected hepatic cells grown big vacuoles in the cytoplasm. The boundary between red pulp and white pulp turned indistinct, splenic corpuscle lost the normal structure, the number and size of melano-macrophage centers increased apparently in the infected spleen. The whole structure of head kidney became loose. Immunostaining with RNA probes against piscidin 5-like showed subpopulations of mast cells (MCs) were positive. Piscidin 5-like-positive MCs existed mainly in the head kidney where they distributed around melano-macrophage center, followed in the gill located at different positions they also distributed in the margin of spleen, and randomly and sparsely existed in the liver. After being infected by C. irritans, the gill arch arose positive MCs groups, and they also migrated to spleen, while the positive staining deepen in other detected tissues. Therefore, organism enhanced the expression level through improving expression ability of positive MCs, or increasing the number of positive MCs.

Scuticociliatosis caused by Uronema sp. in ten different ornamental aquarium reef fish in Brazil / Scuticociliatose causado por Uronema sp. em dez diferentes peixes ornamentais de recife no Brasil

Abstract Scuticociliatosis, caused by an opportunistic ciliate protozoan, is responsible for significant economic losses in marine ornamental fish. This study reports the occurrence of Uronema spp., parasitizing ten species of marine reef fish at an ornamental fish wholesaler: Blue green damselfish (Chromis viridis), Vanderbilt's Chromis (Chromis vanderbilti), Pennant coralfish (Heniochus acuminatus), Threespot angelfish (Apolemichthys trimaculatus), Goldspotted angelfish (Apolemichthys xanthopunctatus), Sea goldie (Pseudanthias squamipinnis), Orchid dottyback (Pseudochromis fridmani), Threadfin butterflyfish (Chaetodon auriga), Vagabond butterflyfish (Chaetodon vagabundus), and Bluecheek butterflyfish (Chaetodon semilarvatus). Diseased fish showed disorders such as hemorrhages and ulcerative lesions on the body surface. Histopathological analysis of the muscle, liver, gut, kidney, spleen, gills, and stomach revealed hemorrhages and degeneration of muscle fiber, vacuolar degeneration of hepatocyte, inflammatory process and granuloma in the liver, atrophy of intestinal villi, inflammatory process and granuloma in the kidney, melanomacrophage centers, as well as inflammatory process in the spleen, epithelial cells hyperplasia and granuloma formation in the gills, and vacuolar degeneration and eosinophils in the stomach. Due to the severity of the disease, it is necessary to implement biosecurity measures with rapid and accurate diagnosis to minimize the risk of economic losses caused by Uronema spp.

Resumo Scuticociliatose, causada pelo protozoário ciliado oportunista, é responsável por significativas perdas econômicas em peixes marinhos ornamentais. O estudo relata a ocorrência de Uronema spp., parasitando dez espécies de peixes de recife em um distribuidor de peixes ornamentais: "Blue green damselfish" (Chromis viridis), "Vanderbilt's Chromis" (Chromis vanderbilti), "Pennant coralfish" (Heniochus acuminatus), "Threespot angelfish" (Apolemichthys trimaculatus), "Goldspotted angelfish" (Apolemichthys xanthopunctatus), "Sea goldie" (Pseudanthias squamipinnis), "Orchid dottyback" (Pseudochromis fridmani), "Threadfin butterflyfish" (Chaetodon auriga), "Vagabond butterflyfish" (Chaetodon vagabundus), e "Bluecheek butterflyfish" (Chaetodon semilarvatus). Peixes doentes apresentaram distúrbios como hemorragias e lesões ulcerativas na superfície do corpo. A análise histopatológica do músculo, fígado, intestino, rim, baço, brânquias e estômago revelou hemorragias e degeneração das fibras musculares, degeneração vacuolar de hepatócitos, processo inflamatório e granuloma no fígado, atrofia das vilosidades intestinais, processo inflamatório e granuloma no rim, centros de melanomacrófagos e processo inflamatório no baço, hiperplasia das células epiteliais, bem como formação de granuloma nas brânquias e degeneração vacuolar e eosinófilos no estômago. Devido à gravidade da doença, é necessário implementar medidas de biossegurança com diagnóstico rápido e preciso para minimizar o risco de perdas econômicas causadas por Uronema spp.

Epidemiology and identification of two species of Chilodonella affecting farmed fishes in China.

The genus Chilodonella includes free-living ciliated protozoa as well as pathogenic species for freshwater fish, with Chilodonella hexasticha and Chilodonella piscicola being the most important ones. These parasites cause outbreaks with high mortalities among farmed freshwater fishes with great economic losses. There are few reports of these species in China, and their identification has been based mostly on their morphological characteristics. In the present work, the parasites causing five outbreaks occurring in China between 2014 and 2017 have been identified by morphological and genetic analysis. We provide the first records of Ctenopharingodon idella and Siniperca chuatsi as hosts of C. hexasticha, and of Procypris rabaudi and Schizothorax wangchiachii as hosts of C. piscicola. There are no differences in the gross pathological findings produced by C. hexasticha and C. piscicola, consisting in desquamation and necrosis of epithelial cells in the skin and gills and in severe fusion of gill lamellae. However, both species differ in their geographic distribution: C. piscicola was found in farms located at altitudes over 1500 m above sea level and with a water temperature ≤18 °C, while C. hexasticha was found in farms located at altitudes under 50 m above sea level and with a water temperature ≥21 °C. Present results confirm that C. hexasticha and C. piscicola are two different species that can be differenced by their morphology; however, their biological variability may lead to erroneous identifications and the diagnosis should be preferably based in genetic analysis including nuclear LSU rDNA and mitochondrial SSU rDNA sequences.

Current status of parasitic ciliates Chilodonella spp. (Phyllopharyngea: Chilodonellidae) in freshwater fish aquaculture.

Freshwater fish farming contributes to more than two-thirds of global aquaculture production. Parasitic ciliates are one of the largest causes of production loss in freshwater farmed fishes, with species from the genus Chilodonella being particularly problematic. While Chilodonella spp. include 'free-living' fauna, some species are involved in mortality events of fish, particularly in high-density aquaculture. Indeed, chilodonellosis causes major productivity losses in over 16 species of farmed freshwater fishes in more than 14 countries. Traditionally, Chilodonella species are identified based on morphological features; however, the genus comprises yet uncharacterized cryptic species, which indicates the necessity for molecular diagnostic methods. This review synthesizes current knowledge on the biology, ecology and geographic distribution of harmful Chilodonella spp. and examines pathological signs, diagnostic methods and treatments. Recent advances in molecular diagnostics and the ability to culture Chilodonella spp. in vitro will enable the development of preventative management practices and sustained freshwater fish aquaculture production.

First record of protozoan parasites in cyprinid fish, Schizothorax niger Heckel, 1838 from Dal lake in Kashmir Himalayas with study on their pathogenesis.

Trichodina heterodentata Duncan, 1977 and Ichthyophthirius multifiliis Fouquet, 1876 obtained from gills during a parasitological survey conducted for the protozoan parasitic fauna of Schizothorax niger a snow trout in Dal Lake, Kashmir, India during the period October 2013 and March 2015. Thirty out of 180 fish were found infected with protozoan parasites. During the study of their pathogenecity the most common deteriorating signs observed in gill tissue were necrosis, hypertrophy, hyperplasia and fusion of secondary lamellae. Prevalence of infection was found to be 16.66%. This is the first record of the protozoan fauna of the schizothoracines from Kashmir valley, India.

Co-infection of Nucleospora cyclopteri (Microsporidia) and Kudoa islandica (Myxozoa) in farmed lumpfish, Cyclopterus lumpus L., in Norway: a case report.

This study describes a co-infection of Kudoa islandica (Myxozoa) and Nucleospora cyclopteri (Microsporida) in farmed lumpfish, Cyclopterus lumpus L., in Norway. Several other parasites (Cryptocotyle sp., protozoan ciliates and Gyrodactylus sp.) were also found in gills. In June 2013, the mortality in a farmed lumpfish population increased to 65%. Lumpfish showed erratic swimming behaviour and loss of weight. At necropsy, nodules in the kidney were the only visible lesions. Histologically, all fish showed severe changes with gill inflammation and necrosis in the spleen, kidney and liver. Haemorrhages and necrosis were observed in some hearts. Intracellular microsporidians associated with the lesions were detected in most organs using histological examination and Calcofluor White. Kudoa spores were diagnosed in the skeletal muscle, but no inflammatory response was associated with the presence of the plasmodia. Comparison of 18S ribosomal DNA sequences showed 100% similarity to Kudoa islandica and Nucleospora cyclopteri. Kudoa islandica and N. cyclopteri have previously been described associated with lesions in wild lumpfish in Iceland. In the present case, N. cyclopteri is believed to be the main cause of systemic pathology. This is the first description of K. islandica and N. cyclopteri causing pathology in farmed lumpfish in Norway.

Mortality in northern corroboree frog tadpoles (Pseudophryne pengilleyi) associated with Tetrahymena-like infection.

CASE REPORT: Mortality of northern corroboree frog tadpoles and eggs occurred in association with Tetrahymena-like ciliates. The predominant lesions in the tadpoles were inflammation and necrosis of the dermis and skeletal muscle. Some of the egg capsules also contained ciliates, but were overgrown with bacteria and fungi. CONCLUSION: Disease occurred, secondary to underlying husbandry issues, and resolved following their correction.

Comparative study of infection with Tetrahymena of different ornamental fish species.

Tetrahymena is a ciliated protozoan that can infect a wide range of fish species, although it is most commonly reported in guppies (Poecilia reticulata). The aim of this study was to compare the susceptibility to infection with Tetrahymena of five different ornamental fish species from two different super orders. The species examined were platy (Xiphophorus), molly (Poecilia sphenops) and angelfish (Pterophyllum scalare) of the Acanthopterygii super order (which also includes guppies) and goldfish (Carassius auratus auratus) and koi carp (Cyprinus carpio) of the Ostariophysi super order. These two super orders are phylogenetically distant from each other. Infection with Tetrahymena resulted in parasite invasion of internal organs, skin and muscle in all fish species. A relatively strong inflammatory response was observed in infected goldfish and koi, with negligible response in fish species of the Acanthopterygii super order. Guppies were the most susceptible to Tetrahymena infection, exhibiting a mortality rate of 87% and 100% in two separate experiments. A high mortality rate was also observed in platy (77%), while that of molly and angelfish was significantly lower (23% and 33%, respectively). Goldfish and koi carp were less susceptible to infection compared with guppies (24% and 59% mortality, respectively). Immunization studies revealed that the Tetrahymena are immunogenic, since infection of koi carp increased their Tetrahymena immobilization response by approximately three-fold at 3 weeks post infection, while immunization with Tetrahymena plus adjuvant increased their immobilization response by approximately 30-fold.

Trichodina heterodentata (Ciliophora) infestation on Prochilodus lineatus larvae: a host-parasite relationship study.

Prochilodus lineatus is a freshwater fish species found in South America. It is common in aquaculture, but few studies regarding diseases of this fish have been performed. This study presents data of the occurrence of Trichodina heterodentata Duncan, 1977, as well as the pathological alterations detected by light and scanning electron microscopy (SEM). Twenty 20-day-old larvae were harvested from an earth pond and examined. Larvae showed erratic swimming on the pond edges and some had a whitish tegument. Larval smears were either impregnated with silver nitrate or stained with Giemsa stain to observe the taxonomic features of the ciliates. Five larvae were fixed in formalin solution for histopathological analysis, and another five specimens were fixed in glutaraldehyde for SEM. All larvae were diagnosed with a severe infestation by trichodinid T. heterodentata. Histological sections showed discrete hyperplasia of the gill filaments with subepithelial oedema of the secondary lamellae. In the SEM, suction areas were observed on the skin, gill and eye; corrosion and ulceration of the fins were associated with the bacterial presence of cocci on the lesions. This is the first report of T. heterodentata in P. lineatus that is responsible for an acute disease that culminates in larval mortality.

Systemic Scuticociliatosis (Philasterides dicentrarchi) in sharks.

Scuticociliatosis is an economically important, frequently fatal disease of marine fish in aquaculture, caused by histophagous ciliated protozoa in the subclass Scuticociliatida of the phylum Ciliophora. A rapidly lethal systemic scuticociliate infection is described that affected aquarium-captive zebra sharks (Stegostoma fasciatum), Port Jackson sharks (Heterodontus portusjacksoni), and a Japanese horn shark (Heterodontus japonicus). Animals died unexpectedly or after a brief period of lethargy or behavioral abnormality. Gross findings included necrohemorrhagic hepatitis and increased volumes of celomic fluid. Histologically, 1 or more of a triad of necrotizing hepatitis, necrotizing meningoencephalitis, and thrombosing branchitis were seen in all cases, with necrotizing vasculitis or intravascular fibrinocellular thrombi. Lesions contained variably abundant invading ciliated protozoa. Molecular identification by polymerase chain reaction from formalin-fixed tissues identified these as the scuticociliate Philasterides dicentrarchi (syn. Miamiensis avidus), a novel and potentially emergent pathogen in sharks.

Trichodina xenopodus, a ciliated protozoan, in a laboratory-maintained Xenopus laevis.

A postmortem evaluation of a domestically bred, adult, female Xenopus laevis revealed the presence of a urinary bladder protozoan consistent with Trichodina xenopodus. T. xenopodus is considered an incidental finding, as its presence in the urinary bladder in frogs has not been correlated with disease or with urinary bladder epithelial lesions. Trichodina spp. are ciliated protozoa known to colonize many species of amphibians and fish. These protozoa frequently inhabit the skin and gills, but may also be present in the urinary bladder of infected animals. Their presence on the skin and gills in low numbers is not related to disease; however, large numbers may indicate poor water quality and overcrowding.

Pathologic findings in weedy (Phyllopteryx taeniolatus) and leafy (Phycodurus eques) seadragons.

A retrospective study of the pathologic findings in weedy (Phyllopteryx taeniolatus) and leafy (Phycodurus eques) seadragons was performed on specimens submitted to 2 reference laboratories from 1994 to 2012 to determine the range and occurrence of diseases affecting aquarium-held populations. One hundred two and 94 total diagnoses were recorded in weedy and leafy seadragons, respectively. Two of the more common etiologic diagnoses in both species were mycobacteriosis and scuticociliatosis, whereas myxozoanosis was common in weedy seadragons. Metazoan parasite infections were less common etiologic diagnoses. There were no correlations between mycobacteriosis and ciliate protozoan infections in either species. Myxozoanosis was usually found in combination with other diseases and, except for 1 case, was restricted to weedy seadragons. Phaeohyphomycosis, nonmycobacterial bacterial infections, and trauma were also important but less frequent diagnoses. Intestinal coccidiosis was found in weedy but not leafy seadragons. Mineralization of the swim bladder was detected in 26 of 197 leafy seadragons and only 2 of 257 weedy seadragons. Although weedy and leafy seadragons share certain diseases of significance to exhibit populations, there are diseases unique to each species about which the veterinary pathologist, clinician, or diagnostician should be aware.

First record of Chilodonella hexasticha (Ciliophora: Chilodonellidae) in Brazilian cultured fish: a morphological and pathological assessment.

Chilodonelids are small ciliated protozoans found worldwide and can be dangerous in culture conditions. This study presents morphometric data on the ciliate Chilodonella that is found in cultured Nile tilapia (Oreochromis niloticus), native bait fish tuvira (Gymnotus aff. inaequilabiatus) and native pacu (Piaractus mesopotamicus) and includes a histopathological assessment of the changes that occur in the pacu. For parasitic diagnosis, skin and gill samples were scraped onto slides, dried at room temperature, stained with Giemsa or impregnated with silver nitrate, and the measurements were obtained from photomicrographs. In the diseased pacu, the first gill arch was collected and fixed in a 10% buffered formalin solution for histopathological analysis. Parasite specimens from the different collection sites were identified morphologically as C. hexasticha Kiernik (1909). Diseased fish exhibited depigmentation, skin ulceration, scale loss, excessive mucus production and gill lesions. Histopathological analysis of pacu gills displayed epithelial proliferation with mononuclear inflammatory infiltrate, hemorrhages, and scattering necrosis. In Brazilian-farmed fish this is the first record of C. hexasticha, which has great pathogenic potential in cultured freshwater species. In addition, two new hosts are presented.

Susceptibility of three strains of blue catfish, Ictalurus furcatus (Valenciennes), to Ichthyophthirius multifiliis.

This study compared the susceptibility of three blue catfish strains (D&B, USDA 101 and USDA 102) to the parasite Ichthyophthirius multifiliis (Ich). In Trial I, a cohabitation study (all strains stocked communally) was conducted and fish were exposed to theronts at 0, 200, 1000, 5000 or 25 000 theronts fish(-1), respectively. All fish died when exposed to theronts at 5000 or 25 000 theronts fish(-1). When exposed to 1000 theronts fish(-1), USDA 102 strain of blue catfish showed significantly lower mortality (78.5%) compared to USDA 101 and D&B strains (92.7% and 100%). In Trial II, the same three strains of blue fish were evaluated for their susceptibility to Ich with strains challenged in separate tanks by adding Ich theronts at 0, 200 and 1000 theronts fish(-1), respectively. All D&B and USDA 101 blue catfish died; however, 42.3% of USDA 102 strain survived the infection when exposed to 1000 theronts per fish. The results indicate that there are differences among strains of blue catfish for susceptibility to Ich, and these differences will be useful in the development of improved catfish germplasm for commercial aquaculture.

Effect of Ichthyophthirius multifiliis parasitism on the survival, hematology and bacterial load in channel catfish previously exposed to Edwardsiella ictaluri.

The effect of Ichthyophthirius multifiliis (Ich) parasitism on survival, hematology and bacterial load in channel catfish, Ictalurus punctatus, previously exposed to Edwardsiella ictaluri was studied. Fish were exposed to E. ictaluri 1 day prior to Ich in the following treatments: (1) infected by E. ictaluri and Ich at 2,500 theronts/fish; (2) infected by E. ictaluri only; (3) infected by Ich at 2,500 theronts/fish only; and (4) non infected control. Mortality was significantly higher in fish previously exposed to E. ictaluri and then infected by Ich (71.1 %). Mortalities were 26.7 %, 28.9 % and 0 % for fish infected by E. ictaluri only, by Ich only and non-infected control, respectively. Quantitative polymerase chain reaction demonstrated the presence of E. ictaluri in the brain, gill, kidney and liver of fish infected with E. ictaluri regardless of Ich parasitism. At day 8, E. ictaluri parasitized fish had significantly more bacteria present in the brain, gill and liver, with no bacteria detected in these organs in the E. ictaluri-only treatment, suggesting that the bacteria persisted longer in parasitized fish. Decreased red blood cells count and hematocrit in fish at days 8 and 19 after co-infection suggests chronic anemia. Lymphocyte numbers significantly decreased in all infected treatments versus the non-infected controls at days 2, 8 and 19. Lymphopenia suggests that lymphocytes were actively involved in the immune response. Bacterial clearance was probably influenced by the stress of parasitism and/or the mucosal response induced by ectoparasitic Ich that resulted in the higher mortality seen in the co-infected treatment.

Philasterides dicentrarchi, a histophagous ciliate causing scuticociliatosis in olive flounder, Philasterides dicentrarchi--histopathology investigations.

Philasterides dicentrarchi is a histophagous scuticociliate infecting Korean olive flounder farms in Jeju Island, South Korea, where it causes significant economic losses. However, the route of entry of these parasites in olive flounder is currently unknown. In the present study, we attempted experimental infection with different doses (concentrations) of P. dicentrarchi by intraperitoneal (IP) injection; maximum cumulative mortality of 95% was recorded on the administration of 2.1×10(8) ciliates/ml. In small size group (3 cm length, 24±2 gwt) the ciliates were found in connective tissues of muscle, fins, and nervous tissue while in large size group (5 cm length, 47±3 gwt), the ciliates were predominantly occurred with associated symptoms of liquefaction in the central nervous system. The major clinico-pathological manifestations were loss of scales, appearance of bleached spots that coalesced to form brownish patches, hemorrhagic, and severe dermal necrotic lesion. In addition there was degeneration of muscle fibers, necrosis of the hepatic parenchyma, and severe edema of the intestinal walls, extensive fouling, necrotic degeneration and hyperplasia in the gill bronchial epithelium. In this study, many ciliates were found in the blood vessel, brain, dorsal fins, muscle, kidney, and vertebra of infected flounder. The histopathological investigations are of significant importance in view of possible routes of entry into the host and doses of ciliates that trigger fast infection for potential utility of drugs as a strategy for the control of P. dicentrarchi in farmed olive flounder.

In vivo innate immune responses of groper (Polyprion oxygeneios) against Miamiensis avidus infection and lack of protection following dietary vitamin C administration.

Scuticociliates are extracellular histophagous parasites that affect farmed fish worldwide. One of the most common pathogenic species is Miamiensis avidus, a pathogen of New Zealand groper (Polyprion oxygeneios). The aim of this study was to characterise both the host (groper)-parasite (M. avidus) immune interactions and the possible protective role of dietary sodium ascorbate. Head-kidney leucocytes (HKLs) from naturally infected adult groper showed decreased respiratory burst response and peroxidase (Px) levels than healthy individuals. Infected groper also had significantly higher serum Px levels compared to controls. Myeloperoxidase (MPO) was inhibited in the head-kidney (HK) whereas MPO(+) cells were observed in the skin and muscle lesions. The inhibition of the innate immune responses was further studied in experimental infections with M. avidus, which confirmed depletion of Px inside leucocytes and marked increases in serum Px in infected individuals. Groper juveniles were fed a diet supplemented with sodium ascorbate (Vitamin C) (2g Kg(-1)) for 21 days and then challenged by subcutaneous injection or immersion exposure with live M. avidus cells. No protection was observed in the sodium ascorbate fed groper compared to the control diet following challenge by either injection or immersion. In vitro assays showed that sodium ascorbate itself results in the inhibition of Px and respiratory burst of groper HKLs, supporting the results obtained in vivo. Our results show that histophagous protozoa such as M. avidus hamper innate immune defences of fish hosts and that dietary sodium ascorbate does not protect groper against experimental infection with this parasite.